Transcatheter valve having reduced seam exposure

ABSTRACT

A transcatheter valve having an expandable frame and a collapsible multi-portion skirt within the frame are provided with seams between the portions of the skirt that are located to cooperate with features of the frame and thereby reduce the exposure of the seams.

RELATED APPLICATIONS

This application is a Division of and claims the benefit of U.S. patentapplication Ser. No. 13/310,949, filed Dec. 5, 2011. The disclosures ofwhich are herein incorporated by reference in their entirety.

TECHNICAL FIELD

This invention relates to transcatheter valves, such as heart valves,which have an expandable frame and a collapsible multi-portion skirtwithin the frame. Such assemblies are suitable for percutaneoustransluminal delivery to replace a diseased aortic valve in patientssuffering from cardiac valve dysfunction, such as aortic valveregurgitation or aortic stenosis.

BACKGROUND

Recently developed transcatheter valves conform to a patient's anatomywhile providing a uniform degree of rigidity and protection for criticalvalve components. They are capable of deforming circumferentially toadapt to the shape of the pre-existing valve annulus, but are notsusceptible to deformation or migration due to normal movement of theheart. In one type of design, the valve prosthesis has a multi-levelcomponent that is anatomically shaped when deployed, thereby enhancinganchoring of the valve and reducing the risk of migration andparavalvular leaks. A particularly successful assembly of this type isdisclosed in U.S. Pat. No. 7,914,569, the entire contents of which isincorporated by reference.

SUMMARY

It has been discovered that the assembly of the type is disclosed inU.S. Pat. No. 7,914,569 may be improved by using differently formedcomponents for the valve skirt, such that improved performance may beachieved without any departure from the successful design disclosed inthat patent. Specifically, it has been discovered that the profile(diameter) of the assembly prior to deployment may be reduced byrearranging certain aspects of the assembly to reduce the bulk of theassembly and exploit the structure of the frame portion of the assemblyto maintain the reduced bulk after deployment.

To accomplish these advantages, an improved valve prosthesis comprises aself-expanding frame having a longitudinal axis and an inflow end, andcomprising a plurality of cells; a valve body having a skirt with abottom edge sewn to the inflow end of the frame, a plurality of leafletssewn to the skirt along a seam having upper and lower halves, a lowerapex region, and at least one side seam between a point on the lowerhalf of the seam (most preferably, the lower apex itself) and the bottomedge. The side seam may be substantially parallel to the longitudinalaxis or it may make an acute angle with the longitudinal axis.

Regardless of angle, the skirt preferably has three substantiallyidentical portions, with each portion being asymmetric about an axissubstantially aligned with the longitudinal direction. However, in lesspreferred embodiments, non-identical portions are possible.

Or, alternatively, the skirt may have three substantially identicalportions, the bottom edge of each portion having five end tabssymmetrically arranged about an axis of the skirt which is substantiallyaligned with the longitudinal direction and passes through an upper apexof the portion. In this case, the side seam extends between the lowerapex region and an end tab which does not lie on the axis of the skirt.

Another variation has the skirt aligned with the frame such that theside seam substantially follows a line defined by three immediatelyadjacent nodes.

In any of the variations described above, it is preferred that the skirtbe aligned with the frame such that the side seam and a line defined bythree immediately adjacent nodes are aligned with each other within ±1mm.

This summary of the claims has been presented here simply to point outsome of the ways that the claims overcomes difficulties presented in theprior art, and to distinguish the claims from the prior art, but it isnot intended to operate in any manner as a limitation on theinterpretation of claims that are presented initially in the patentapplication and that are ultimately granted.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other advantages and features will be more readily understoodfrom the following detailed description of various preferredembodiments, when considered in conjunction with the drawings, in whichlike reference numerals indicate identical structures throughout theseveral views, and in which:

FIG. 1 is a side view of a fully assembled valve body with thesurrounding frame omitted for clarity.

FIG. 2 is a close-up side view of the inflow end of a fully assembledvalve body, including the surrounding frame, according to the embodimentin which the side seam is essentially parallel with the direction offlow (bottom to top in the figure).

FIG. 3 is a close-up side view of the inflow end of a fully assembledvalve body, including the surrounding frame, according to an alternativeembodiment in which the side seam is angled with respect to thedirection of flow (again, bottom to top in the figure).

FIG. 4 is a close-up inverted perspective view of the interior of theembodiment of FIG. 3.

FIG. 5 is a schematic plan view of a portion of the valve skirtaccording to the embodiment of FIGS. 1 and 2.

FIG. 6 is a schematic plan view of a portion of the valve skirtaccording to the embodiment of FIGS. 3 and 4.

FIG. 7 is a partially assembled valve skirt according to the embodimentof FIG. 5.

FIG. 8 is a partially assembled valve skirt according to the embodimentof FIG. 6.

FIGS. 9 and 10 are partially assembled valve skirts according to otherembodiments.

DETAILED DESCRIPTION

In the following detailed description, references are made toillustrative embodiments of methods and apparatus for carrying out theclaims. It is understood that other embodiments can be utilized withoutdeparting from the scope of the claims.

By way of background, the currently successful transcatheter aorticvalve prosthesis known by the tradename CoreValve® (Medtronic, Inc.) hasa self-expanding multi-level frame which supports a valve bodycomprising a skirt and plurality of coapting leaflets. The frame has acontracted delivery configuration, in which the prosthesis may be storedwithin a catheter for percutaneous delivery, and an expanded deployedconfiguration having an asymmetric hourglass shape. The valve body skirtand leaflets preferably are constructed of porcine, bovine, equine orother mammalian tissue, such as pericardial tissue, and are sewn,welded, molded or glued together so as to efficiently distribute forcesalong the leaflets and to the frame. Alternatively, the valve body maycomprise a synthetic or polymeric material. The frame comprises multiplelevels, including a proximal conical inflow section, a constrictionregion and a flared distal outflow section. Each of the inflow andoutflow sections is capable of deforming to a non-circular cross-sectionto conform to the patient's anatomy, while the constriction region isconfigured to retain a circular cross-section that preserves properfunctioning of the valve body. The frame comprises a plurality of cellshaving a pattern that varies along the length of the frame to provide ahigh degree of anchoring and alignment of the valve prosthesis. The cellpattern further is selected to provide a uniform diameter where thecommissural joints of the leaflets are attached to the frame, whilepermitting the inflow and outflow regions to expand to conform to thepatient's anatomy. In this manner, optimal functioning of the valve bodymay be obtained even though the frame may be deployed in anatomieshaving a range of sizes. In addition, the frame resists deformationcaused by movement of the heart and enables a functional portion of thevalve body to be disposed supra-annularly to the native valve, with aportion of the valve prosthesis extending into the native valve annulus.For aortic valve replacement, the valve body comprises a skirt coupledto three leaflets. Each of the components preferably is formed of animalpericardial tissue or synthetic material, and then sewn, glued, weldedor molded together. The lateral ends of the leaflets include enlargedregions that are folded to both form the commissural joints and fastenthe commissural joints to the frame. The skirt and leaflets further areconfigured so that the joints align with contours of the cell pattern ofthe frame. In a preferred embodiment, the commissural joints are affixedto the frame at locations above the area of coaptation, to provide aselectable center of coaptation of the leaflets. This design provides amore efficient delivery configuration because the commissures are notcompressed against the leaflets when the valve prosthesis is reduced tothe contracted delivery configuration. Additionally, by lengthening thedistance to the commissures, the design mimics the functioning ofnatural tissue valves by distributing forces along the coaptation edgesand reducing horizontal forces transmitted to the commissural joints.

In general terms, the valve prosthesis includes a self-expanding framewhich supports a valve body and has a tri-level asymmetric hourglassshape with a conical proximal section, an enlarged distal section and aconstriction region having a predefined curvature when the frame isdeployed. The proximal section constitutes the “inflow” portion of thevalve prosthesis and is disposed in the aortic annulus of the patient'sleft ventricle, while the distal section constitutes the “outflow”portion of the valve prosthesis and is positioned in the patient'sascending aorta. In a preferred embodiment the valve body comprisesthree leaflets that are fastened together at enlarged lateral endregions to form commissural joints, with the unattached edges formingthe coaptation edges of the valve. The leaflets are fastened to a skirt,which is in turn affixed to the frame. The enlarged lateral end regionsof the leaflets permit the material to be folded over to enhancedurability of the valve and reduce stress concentration points thatcould lead to fatigue or tearing of the leaflets. The commissural jointsare mounted above the plane of the coaptation edges of the valve body tominimize the contracted delivery profile of the valve prosthesis, whilethe configuration of the edges permits uniform stress distribution alongthe coaptation edges.

The frame preferably comprises a self-expanding structure formed bylaser cutting or etching a metal alloy tube comprising, for example,stainless steel or a shape memory material such as nickel titanium. Theframe has an expanded deployed configuration which is impressed upon themetal alloy tube using conventional techniques.

Referring now to FIG. 1, the valve prosthesis of this applicationcontinues the successful features of the prosthesis described above butimproves upon it. In more specific terms, the valve prosthesis comprisesvalve body 14. Valve body 14 includes skirt 21, and leaflets 22.Leaflets 22 are attached along their bases to skirt 21, for example,using sutures or a suitable biocompatible adhesive. Adjoining pairs ofleaflets are attached to one another at their lateral ends to formcommissures 24, with free edges 25 of the leaflets forming coaptationedges that meet in an area of coaptation, as described more fully inU.S. Pat. No. 7,914,569, the entire contents of which are incorporatedby reference.

The curve formed at joint 27 between the base of each leaflet 22 andskirt 21 follows the contour of the cell pattern of the frame (not shownin FIG. 1), so that most of the length of joint 27 is directly supportedby the frame, thereby transmitting forces applied to the valve bodydirectly to the frame.

Skirt 21 and leaflet 22, in preferred embodiments, may be cut from asheet of animal pericardial tissue, such as porcine pericardial tissue,although synthetic or polymeric material may be used. Cutting may bedone either manually or using a die or laser cutting system. Thepericardial tissue may be processed in accordance with conventionaltechniques for processing, forming and treating tissue valve material.Alternatively, skirt 21 and leaflet 22 may be constructed on a syntheticor polymeric material. In a preferred embodiment, skirt 21 and leaflets22 have a thickness of between 0.004 inch and 0.016 inch. Thethicknesses of skirt 21 and leaflets 22 may or may not be equal to eachother.

Skirt 21 comprises at least one side seam 43 where skirt 21 is joinedupon itself (in a one-piece embodiment) or where two portions ofmaterial are joined to each other as part of the assembly of skirt 21from separate components (three, in the preferred embodiment). In anycase, side seam 43 extends downwardly from a point on the lower half ofjoint 27, preferably from a point in the apex region (i.e., theimmediate vicinity of the apex) and most preferably (as illustrated),from the lower apex of joint 27. Side seam 43 extends downwardly towardsthe inflow portion of the prosthesis until it reaches the lower (orinflow) edge of skirt 21 located within the region indicated by I.Turning to FIG. 2, it may be seen that skirt 21 is attached to the framesuch that the side seam 43 extends only the relatively short distancerepresented by a single cell of the frame. One advantage of such anembodiment is the reduction in the amount of any biological response tothe seams, e.g., coagulation triggered by stitches or tissue folds.

FIGS. 3 and 4 illustrate an alternative embodiment in which side seam 43is angled with respect to the vertical (i.e., the longitudinal axislying along the direction of flow through the valve 10). In thisembodiment, the side seam 43 is somewhat longer than in the embodimentof FIG. 2, because side seam 43 lies generally aligned with the diagonalstruts 60 extending between three consecutive nodes 61 of the frame, asopposed to spanning the open portion of a cell. Nonetheless, side seam43 is still significantly shorter than it would be if it extended to a apoint on the upper half of joint 27 (e.g., locations where individualjoints 27 come together). This embodiment has the advantage of orientingthe side seam 43 behind the frame (compare FIGS. 3 and 4) to avoid a“pillow” effect, i.e., a tendency for side seam 43 to bulge outwardlyfrom the interior of the frame.

FIGS. 5 and 6 schematically illustrate various geometrical features of aportion of skirt 21 corresponding to the embodiments of FIGS. 2 and 3-4,respectively. FIGS. 7 and 8 illustrate the assembly of the portions ofFIGS. 5 and 6, respectively.

Skirt 21 preferably is constructed from the same material as leaflets22, and includes scalloped areas 37 a-b, reinforcing tabs 38 a-b andmultiple end tabs 39. Each scalloped area 37 a-b is shaped to be joinedto each other and then joined to a body 33 of a respective leaflet 22,as described illustrated earlier (see FIG. 1). Reinforcing tabs 38 a-binclude fold lines (not shown in FIG. 6 for clarity), except forreinforcing tabs 40 and 41 at the lateral ends of the skirt, which haveonly one fold apiece (see FIGS. 7-8). As described below, reinforcingtabs 40 and 41 are joined to one another, e.g., by sutures or gluing, sothat skirt 21 forms a frustum of a cone. End tabs 39 are folded over theends of the proximal-most row of cells of the frame to secure skirt 21to the frame and seal against paravalvular bypass flows.

A line of symmetry S passes through a location substantially centered onthe upper apex 50, and is substantially parallel to the longitudinaldirection of flow. Notably, in the embodiment of FIG. 5, line Ssymmetrically divides tabs 39 a-e but does not symmetrically divide suchtabs 39 b-f in the embodiment of FIG. 6. This is due to the notabledifference between the embodiments, i.e., the acute angle θ that sideseam 43 makes from the direction of flow in FIG. 6, which enables sideseam 43 (in that embodiment) to follow the frame as described above.Note that side seam 43 still originates in the lower apex region,specifically at lower apex 52 (the vertex of the acute angle). It mayalso be said that the side seam 43 extends between the lower apex 52 andan end tab which does not lie on the axis S, i.e., end tab 39 b or 39 f,as opposed to end tab 39 c which does lie on that axis.

FIGS. 9 and 10 schematically illustrate less preferred embodiments; forthe sake of clarity, some details common to the preferred embodimentsabove are omitted. In these two embodiments, the angled seams originateat higher locations on the joints other than the lower apex but still inthe lower half of the seams. As FIG. 10 shows in particular, theportions of such embodiments do not necessarily have identical shapes.The embodiments of FIGS. 9 and 10 are less preferred than otherembodiments because of their relatively complicated configuration ascompared to the preferred embodiments discussed above, and also becausethe side seams in these embodiments are generally not be a short asthose in the preferred embodiments.

In general, assembly of valve body 14 from skirt 21 and leaflets 22 isperformed as described in U.S. Pat. No. 7,914,569 as modified toaccommodate the modifications described here. Adjoining leaflets 22 thenare fastened together along adjacent seams, resulting in a leafletassembly.

Referring again to FIG. 1, valve body 14 is shown as it would appearwhen affixed to the frame, but with the frame omitted to betterillustrate where the valve body is affixed to the frame. During the stepof affixing the valve body to the frame, flaps 36 of adjacent leafletsare affixed, e.g., by sutures, to span a cell of the frame to supportcommissures 24 and end tabs 39 are folded over and affixed to the mostproximal row of cells of the frame, i.e., at the inflow end to theprosthesis.

Valve body 14 also is attached to the frame along seams 43 formed by thereinforcing tabs. Each joint 44 is aligned with and fastened to (e.g.,by sutures or glue) to a curved contour defined by the struts and nodesthat form the cells of the frame, so that joint 44 is affixed to andsupported by the frame over most of the length of the joint. Asdiscussed above, the configuration of the cells in the frame may bespecifically customized to define a curved contour that supports joints44 of the valve body.

When completely assembled to the frame, valve body 14 is affixed to theframe along the edges of flaps 36 of the commissures, end tabs 39,leaflet seams 42, reinforcing tab seams 43 and joints 44. In thismanner, forces imposed on leaflets 22, commissures 24 and joints 44 areefficiently and evenly distributed over the valve body and transferredto the frame, thus reducing stress concentration and fatigue of thevalve body components.

Implantation of the valve prosthesis is performed in a conventionalmanner.

While the description above uses preferred embodiments to describecertain details, the broadest scope of the disclosure includes otherembodiments, as well as methods of carrying out the same principles thatdo not depend upon the specific physical components mentioned above butnonetheless achieve the same or equivalent results. Therefore, the fullscope of the invention is described by the following claims.

What is claimed is:
 1. A method of manufacturing a valve prosthesiscomprising: providing an expandable frame having a longitudinal axis andan inflow end, and comprising a plurality of cells; providing a valvebody comprising a skirt having a bottom edge; sewing the bottom edge tothe inflow end of the frame; providing the skirt with a plurality ofleaflets attached along a joint curved to have upper and lower portionsas a whole, in which adjacent joints come together in the upper portion,and an apex of a curve lies in the lower portion; and providing theskirt with at least one side seam extending only between the lowerportion of the joint and the bottom edge of the skirt.
 2. The method ofclaim 1, in which the lower portion has a lower apex region, and theside seam extends between the lower apex region and the bottom edge. 3.The method of claim 1, in which the frame comprises struts and nodes;the method further comprising aligning the skirt with the frame suchthat at least one side seam substantially follows a line defined bythree immediately adjacent nodes.
 4. The method of claim 1, in which theframe comprises struts and nodes; the method further comprising aligningat least one side seam and a line defined by three immediately adjacentnodes with each other within ±1 mm.
 5. The method of claim 1, whereinadjoining leaflets are sewn together to form commissures; the methodfurther comprising sewing the commissures to the frame downstream of theinflow end.
 6. The method of claim 1, wherein at least one side seam issubstantially parallel to the longitudinal axis.
 7. The method of claim1, wherein at least one side seam makes an acute angle with thelongitudinal axis.
 8. The method of claim 1, wherein the bottom edgecomprises a plurality of end tabs.